Several thousand Ukrainians have rallied in front of parliament to protest against a deal allowing Russia to keep its navy in Ukraine's Crimea for another 25 years.
Former Prime Minister Yulia Tymoshenko told the rally today that all opposition forces must unite to resist the deal, which was signed on April 21.
The protesters, many from opposition parties, held banners with slogans such as "No to the destruction of national sovereignty" and "Out with the Russian Black Sea Fleet."
Several hundred counterprotesters rallied nearby in support of President Viktor Yanukovych.
A senior official in Ukraine's ruling coalition earlier today criticized Yanukovych for concluding the deal "behind closed doors."
Deputy Prime Minister for economic policy Serhiy Tihipko told AP that secret negotiations are "not what the Ukrainian people want."
The deal extends the Russian lease at the port of Sevastopol after the existing lease expires in 2017.
In exchange for the lease extension, Moscow gave Kyiv a discount on Russian natural gas, which will save Ukraine billions of dollars as it struggles to recover from the economic crisis.
Opposition To Block Ratification
The agreement is due to be submitted to Ukraine's parliament for ratification on April 27, the same day the treaty will be considered in Russia's State Duma.
Tymoshenko called on April 23 for an extraordinary session of parliament in an effort to block ratification of the treaty.
Tymoshenko called for the session of the Verkhovna Rada, Ukraine's unicameral parliament, to be held today.
Tymoshenko told journalists on April 23 that if ratified, the agreement would "remove Ukraine's right to govern part of its territory," adding that the extraordinary parliamentary session would take place even if speaker Volodymyr Lytvyn refuses to preside over the session.
Political scientist Vladimir Fesenko told RFE/RL's Russian Service that the extraordinary session would not indicate whether or not the opposition can form a united stance against the treaty. He said this would only be evident on April 27.
Several opposition leaders, faced with a pro-Yanukovych coalition in parliament, have said they would stall parliamentary proceedings on April 27 and called for mass demonstrations on April 24 and 27.
Fesenko said that although the opposition is divided -- especially by the animosity between former President Viktor Yushchenko and Tymoshenko -- he believed there is a chance the opposition will successfully unite to block ratification of the treaty.
"The fact that almost all the leaders of the opposition have sharply denounced the agreement on the Black Sea Fleet -- is very indicative...[that] the coordination of initiatives of the various opposition forces against the ratification...is definitely possible," Fesenko said.
with agency reports